Coronary artery disease

Question 1

Compare stenotic and non-stenotic lesions in coronary arteries.

Answer 1

1. Stenotic:
   - few
   - fibrotic
   - thick cap
   - less compensatory enlargement
   - manifests as ischaemia: angina pectoris, +ve stress test, perfusion defect
2. Non-stenotic:
   - many
   - lipid-rich
   - thin cap
   - clinically manifests as MI
   - compensatory enlargement

Question 2

What are the signs and symptoms of coronary artery disease?

Answer 2

• chest pain
• indigestion
• nausea and vomiting
• fatigue and sleeping problems

Question 3

Describe the different grades of symptoms relating to coronary artery disease?

Answer 3

• Grade I: chest pain only during physical/emotional stress
• Grade II: chest pain during activities (walking quickly/uphill, climbing stairs etc)
• Grade III: chest pain during low intensity activity - walking, getting dressed etc
• Grade IV: chest pain at rest/during slight physical exertion

Question 4

How can coronary artery disease be diagnosed?

Answer 4

ECG
Blood tests (troponin, CK-MB)
Stress test
Angiography
Echocardiography

Question 5

What is the treatment for coronary artery disease?

Answer 5

1st line: total cholesterol >200mg/dL
- lipid lower, reduce BP, lifestyle changes

Early stage disease: Nitroglycerin, BBs, ACE-Is, others

Late stage disease: Cardiac bypass, surgery + PCI

Question 6

Explain how statins work.

Answer 6

Inhibit HMG CoA reductase
Prevent HMG CoA being converted to mevalonic acid
therefore prevent the formation of cholesterol

Question 7

Explain how nitroglycerin works.

Answer 7

• converted to nitric oxide which activates guanylate cyclase
• induces the synthesis of cGMP
• cGMP activates a series of protein kinase dependent phosphorylations in SMCs
• -> result of that is dephosphorylation of myosin light chain in SM fibres
• this causes the release of Ca2+ = SMC relaxation and vasodilation
• also acts as an agonist of ANP receptor 1

Question 8

What are the side effects of nitroglycerin?

Answer 8

headaches
dizziness
reflex tachycardia

Question 9

Explain how BBs work.

Answer 9

• binds to receptors at the SA node = reduced HR and O2 demand
• binds to receptors at ventricular myocardium = reduced inotropy and O2 demand
• reduced BP (afterload)

Question 10

What are the side effects of BBs?

Answer 10

increased end diastolic volume

increased ejection time

Question 11

Explain how CCBs work.

Answer 11

• blocks influx of Ca2+ via voltage gated L-type Ca2+ channels
• reduced HR and O2 demand at the SA node
• reduced inotropy and O2 demand at ventricular myocardium
• reduced BP

Question 12

What are the side effects of CCBs.

Answer 12

constipation
dizziness
AV and SA node depression

Question 13

Compare the treatment for STEMI and NSTEMI.

Answer 13

STEMI:

• *goal is to break apart fibrin mesh to restore blood flow
• fibrinolytic therapy or PCI

NSTEMI:

• *prevent progression to complete occlusino
• consider GPIIb/IIIa inhibitor + aspirin + heparin before early diagnostic catheterisation